Golf club head

ABSTRACT

A golf club head includes a center of gravity spaced less than 5 mm from a vertical center plane that is perpendicular to a striking face plane and extends through a striking face center. The golf club head also includes a first component having a first melting point and a first density and a second component having a second melting point higher than the first melting point and a second density less than the first density. And the second component (i) is at least partially encapsulated by the first component, (ii) extends into a hosel portion below a hosel bore, and (iii) has a mass less than about 5 g.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 63/032,224. The entire contents of that application are incorporatedby reference herein.

BACKGROUND

This disclosure relates generally to the field of golf clubs. Moreparticularly, it relates to a golf club head with an insert in at leastthe hosel portion of the club head.

A goal of golf club head design is to align the club head's center ofgravity with the location on the striking face most likely to come intocontact with the golf ball during a swing. This increases shot accuracyand helps ensure that as much energy as possible from the golfer's swingis transferred to the golf ball at impact, thereby resulting in afavorable golf shot.

SUMMARY

But this goal can often be difficult to achieve within the constraintsof a given mass budget. This is especially true in connection with“player” iron-type golf club heads, in which the center of gravity ofthe club head is naturally biased toward the heel side from face centerdue to the shaping and weight of the heel and hosel portions. Golferswho use these club heads also often enjoy their more traditional look,and these golfers may thus object to changes designed to beneficiallyalter the weight profile of the club head but that also cause the clubhead to diverge from this traditional look. For example, perimeterweighting may be added to an iron or wedge-type golf club head toincrease its moments of inertia and thereby add “forgiveness” onoff-center hits, but the appearance of such a cavity-back club head canbe off-putting for players who prefer the appearance of blade-type ironsand wedges. A need thus exists for a design that discretely moves weightfrom one portion of the club head to another so as to move the center ofgravity closer to where the golf ball is likely to be struck, mostlikely the face center of the club head, while also providingforgiveness on off-center hits.

A golf club head according to one or more aspects of the presentdisclosure thus includes, when oriented in a reference position, astriking face having a face center and defining a face plane; a verticalcenter plane that is perpendicular to the face plane and extends throughthe face center; a sole portion; a top portion; a heel portion; a toeportion opposite the heel portion; a hosel portion extending from theheel portion and comprising a hosel bore with an open end for receivinga shaft and a bottom surface, the hosel bore defining a central hoselaxis; and a center of gravity spaced less than 5 mm from the verticalcenter plane. The golf club head may also include a first component of afirst material having a first melting point and a first density and asecond component having a second melting point higher than the firstmelting point and a second density less than the first density, thesecond component (i) being at least partially encapsulated by the firstcomponent, (ii) extending into the hosel portion below the hosel bore,and (iii) having a mass less than about 5 g.

A method of manufacturing a golf club head in accordance with one ormore aspects of the present disclosure may in turn include steps of: (a)forming an auxiliary component with an auxiliary material; (b)encapsulating, by an investment casting process, the auxiliary componentwithin a golf club head body comprising a primary material; and (c)removing a portion of the auxiliary component to create a hosel borewith an open end and a bottom surface such that an uppermost extent ofthe auxiliary component is below the bottom surface. The primarymaterial may have a first melting point and a first density, and theauxiliary material may have a second melting point greater than thefirst melting point and a second density less than the first density.And the golf club head may further include: a striking face having aface center and defining a face plane; a vertical center planesubstantially perpendicular to the face plane and passing through theface center; and a center of gravity located less than 5 mm from thevertical center plane.

And another golf club head according to one or more aspects of thepresent disclosure may include a golf club head main body and anauxiliary component. The golf club head main body may in turn include astriking face having a face center and defining a face plane; a verticalcenter plane that is perpendicular to the face plane and extends throughthe face center; a sole portion; a top portion; a heel portion; a toeportion opposite the heel portion; a hosel extending from the heelportion and comprising a hosel bore with an open end and a bottomsurface, the hosel bore defining a central hosel axis; and a firstmaterial having a first melting point and a first density. The auxiliarycomponent may in turn include a heel portion comprising a secondmaterial having a second melting point higher than the first meltingpoint and a second density less than the first density; an upper extentlocated below the bottom surface of the hosel bore; and a toe portionconnected to the heel portion and comprising a third material having adensity greater than the first density. And a center of gravity of thisgolf club head may be located less than 5 mm from the vertical centerplane.

These and other features and advantages of the golf club heads andmanufacturing methods thereof according to the various aspects of thepresent disclosure will become more apparent upon consideration of thefollowing description, drawings, and appended claims. The descriptionand drawings described below are for illustrative purposes only and arenot intended to limit the scope of the present invention in any manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a front elevation view of an exemplary golf club head inaccordance with one or more aspects of the present disclosure;

FIG. 2 shows a rear schematic view of the exemplary golf club head ofFIG. 1;

FIG. 3 shows a heel-side elevation view of an exemplary golf club headin accordance with one or more aspects of the present disclosure;

FIG. 4 shows a cross-section of the golf club head of FIG. 3 along theline IV-IV;

FIG. 5 shows a front perspective view of the golf club head of FIG. 3with the hosel removed;

FIG. 6 shows a cross-section of the golf club head of FIG. 5 along theline VI-VI;

FIG. 7 shows an exemplary method of manufacturing the golf club head ofFIG. 3;

FIG. 8 shows a close-up view of the insert within the golf club head ofFIG. 3;

FIG. 9 shows overlapping club heads as part of a method of designing theinsert of FIG. 8;

FIG. 10 shows a golf club head resulting from a second step of themethod of FIG. 7;

FIG. 11 shows a golf club head resulting from a third step of the methodof FIG. 7;

FIG. 12 shows a golf club head resulting from a fourth step of themethod of FIG. 7;

FIG. 13 shows an exemplary method of manufacturing a golf club head inaccordance with one or more aspects of the present disclosure;

FIG. 14 shows a golf club head resulting from a fourth step of themethod of FIG. 13;

FIG. 15 shows a rear cutaway view of a golf club head in accordance withone or more aspects of the present disclosure;

FIG. 16 shows a heel-side cutaway view of the golf club head of FIG. 15;

FIG. 17 shows a rear schematic view of the golf club head of FIG. 15;

FIG. 18 shows a cross-section of the golf club head of FIG. 17 along theline XVIII-XVIII; and

FIG. 19 shows a cross-section of the golf club head of FIG. 17 along theline XIX-XIX.

DETAILED DESCRIPTION OF EMBODIMENTS

Shown in FIGS. 1 and 2 is a golf club head 100 in accordance with one ormore aspects of the present disclosure. A main body of this golf clubhead may be bounded by a toe portion 110, a heel portion 120 oppositethe toe portion, a top portion 130, and a sole portion 140 opposite thetop portion. A hosel portion 150 for securing the club head to anassociated shaft (not shown) may extend from the heel portion, and thehosel portion may in turn define a virtual central hosel axis 152.

The club head may further include a striking face 160 at a front portionthereof. The striking face is the substantially planar exterior surfacepart of the front portion that generally conforms to a virtual strikingface plane and that is arranged to contact a golf ball at afactory-designated loft angle taken between the striking face plane andthe central hosel axis. The striking face may be formed with surfacefeatures that increase traction between the striking face and a struckgolf ball to ensure both good contact with the ball (for example, in wetconditions) and impart a degree of spin to the ball, e.g., for stabilityin flight or to control better the rest position of a struck golf ballonce it has returned to the ground by way of backspin. Included in thesesurface features may be a plurality of substantially parallel horizontalgrooves or score lines 162 as well as other surface features (not shown)that form a texture pattern. The striking face may include a face center164. Face center, as used herein, refers to the point on the strikingface of the club head that is halfway between the heel-most extent andthe toe-most extent of the score lines 162, and halfway between thetopmost extent and sole-most extent of the score lines. In a golf clubhead where score lines extend to about a toe-side edge of the strikingface, the toe-most extent of the score lines is defined by a virtualvertical plane extending through an apex of the golf club head's topportion. A virtual vertical center plane 166 perpendicular to the faceplane may project through the face center in the front-to-rear directionof the club head, and a center of gravity 170 of the golf club head maybe spaced from that virtual vertical center plane. In FIG. 1, forexample, the center of gravity may be spaced heelward from the virtualvertical center plane. The center of gravity may be spaced by a distance172 less than 5 mm from the virtual vertical center plane, and in morepreferred embodiments, it may be spaced less than 2 mm from that virtualvertical center plane.

The golf club head is shown in FIG. 1 as being in the “referenceposition.” As used herein, “reference position” denotes a position of agolf club head, e.g., the club head of FIG. 1, in which the sole portionof the club head contacts a virtual ground plane 10 such that thevirtual central hosel axis 152 of the hosel portion lies in a virtualvertical hosel plane and the score lines 162 are oriented horizontallyrelative to the ground plane. Unless otherwise specified, all club headdimensions described herein are taken with the club head in thereference position.

The golf dub head of FIGS. 1 and 2 preferably comprises an iron-type dubhead such as a wedge-type dub head, and it may preferably have a loftangle of no less than 40°. More preferably, the golf club head may be atraditional blade-type club head, which may otherwise be referred to asa “player”-type club head by certain golfers. As such, and as shown inFIG. 2, a rear 180 of the club head may include an upper blade portion182 and a lower muscle portion 184. The upper blade portion maypreferably comprise a substantially planar surface, and it may thuspreferably lack any perimeter-weighting features. The muscle portion mayproject rearward from the upper blade portion. Mass of the golf clubhead may be generally concentrated in the muscle portion, so the centerof gravity 170 may be located soleward of the face center. And as shownin FIG. 2 specifically, moment of inertia (“MOI”) Izz 186 of the golfclub head may be measured about a virtual vertical axis 187 passingthrough the center of gravity, and MOI Ixx 188 of the golf club head maybe measured about a virtual horizontal axis 189, parallel to the groundplane, that likewise passes through the center of gravity. As known tothose of ordinary skill in the art, MOI is generally correlated withincreasing the club head's natural resistance to rotation about acertain axis on off-centered golf ball impacts.

The golf club head of one or more aspects of this disclosure preferablyhas an internal structure that, compared to other “player”-type golfclub heads, discretely moves weight from the heel portion or lower hoselportion to the sole/muscle portion or to the top of the hosel portion,thereby moving the center of gravity closer to the face center, i.e.,where experienced golfers are more likely to hit the golf ball on thestriking face, and correspondingly increasing both vertical (Izz) andhorizontal (Ixx) MOI. Exemplary golf club heads having such an internalstructure are described below. Each of these exemplary club heads mayinclude the main body structure described above in connection with FIGS.1 and 2.

FIG. 4 shows a cross-section of a golf club head according to one aspectof the present disclosure taken along line IV-IV in FIG. 3. As shown,the hosel portion 150 of this club head may include a hosel bore 154extending a depth 155 into the hosel portion from an open, topmost end156 of the hosel portion. This bore may possess a top inner diameter 157and a bottom inner diameter 158, which may be the same or may bedifferent. And the hosel bore may terminate at its bottom at a metalshelf 159 that projects inward toward the virtual central hosel axis.The hosel portion sidewall (as well as the remainder of the golf clubhead main body) may constitute a first component preferably formed of aprimary material such as steel and/or a material having a density noless than 8 g/cm³ and/or a melting point below 1600° C. And a minimumthickness 151 of the hosel portion sidewall, preferably measured at abottom of the hosel bore, may be sufficient to ensure structuralintegrity of the hosel portion without negatively affecting vibrationalfeedback on golf shots. For example, this minimum thickness may be noless than 0.5 mm, and more preferably no less than 0.75 mm.

Soleward of the bottom of the hosel bore may be an insert 190 thatserves as a second, or auxiliary, component. The insert may include asubstantially cylindrical portion 192 (FIG. 8) with a central axis thatis coaxial with the virtual central hosel axis. The insert may alsoinclude a heel portion shaped to generally conform to a heel contour ofthe golf club head. This insert may be formed of an auxiliary materialsuch as a ceramic, and it may preferably have a melting point higherthan that of the first component and a density less than that of thefirst component. As such, the insert may have a mass less than about 5 gin the golf club head, and relative to the overall mass of the golf clubhead, the mass of the insert may be less than 1.5%. This insert may bycomposed of at least 60% aluminum oxide (Al₂O₃). More specifically, thisceramic insert may be composed of 20% SiO₂, 10% ZrO₂, and 70% Al₂O₃,although each of these percentages may vary by up to about 10%. Byadjusting the ceramic composition, material properties of the insert maybe tuned to achieve a weight distribution target, e.g., increased momentof inertia, lower and/or centered center of gravity location, or aparticular vibrational frequency upon impact. The insert may alsopossess the following properties: (i) a bonding strength of 15 MPa; (ii)a porosity of no more than 40%, preferably 30%; (iii) absorption of 30%;(iv) a melting point greater than 2500° C.; and (v) a density no greaterthan 3 g/cm³, preferably no greater than 2 g/cm³. But like thecomposition of the insert, the insert's bonding strength, porosity,absorption, and density may vary to achieve a particular weightdistribution target.

As shown in FIG. 6, which shows a cross-section taken at the line VI-VIin FIG. 5, the insert 190 may extend from the hosel portion into theheel portion of the golf club head. And this insert may impact variousMOI values of the golf club head. For example, vertical MOI Izz may begreater than 3,000 g*cm², and horizontal MOI Ixx may be greater than1,000 g*cm².

FIGS. 7-12 show an exemplary method 200 of forming the golf club head ofFIGS. 3-6. In a first step 210, the insert may be formed by, e.g.,injection molding. FIG. 8 shows one embodiment of the insert 190 afterthis first forming step. This insert may preferably be designed byoverlaying various club lofts in a computer-assisted design (“CAD”)program and selecting an overlapping region of those club heads whileaccounting for necessary constraints such as minimal steel wallthickness for integrity of the hosel and/or heel portions. For example,FIG. 9 shows an insert formed in an overlapping area of club headshaving lofts of 46°, 54°, and 64°. This design process may easemanufacturing concerns and provide various cost benefits since a newinsert is not required to be designed for each golf club head loft andsole shape. In one or more embodiments, a minimum steel wall thicknessis no less than 0.5 mm and more preferably no less than 0.75 mm.

In the second step 220 shown in FIG. 7, the golf club head main body maythen be formed, e.g., by investment casting, around the insert 190 so toencapsulate the insert therein. The result of this step is shown in FIG.10, in which the insert is shown to extend not only below the bottommetal shelf 159 of the hosel bore but also through the hosel bore andbeyond the opening at the topmost end 156 of the hosel portion 150. Theupper part 194 of the insert, i.e., the portions extending beyond thetopmost opening of the hosel portion and extending into the hosel bore,may then be removed in the third step 230 shown in FIG. 7 by, e.g.,machining. As shown in FIG. 11, which shows the result of this thirdstep, the hosel bore 154 and topmost end 156 of the hosel portion maynow be open so as to be able to receive a golf club shaft, and theinsert 190 may extend soleward of the metal shelf 159 delimiting thebottom of the hosel bore. As also shown in FIG. 11, the insert may notextend beyond the heel-most extent 163 of the score lines formed on thestriking face. Preferably, the insert may extend to about the heel-mostextent of those score lines. This ensures that the insert does notextend into the hitting zone of the striking face, which may minimizeany change to traditional feel and sound of the golf club head at impactwith the golf ball. And in the final step 240 of FIG. 7, the result ofwhich is shown in FIG. 12, an insert cap 196 may be introduced into thehosel bore so as to rest on the metal shelf 159. This insert cap, whichmay be formed of Al or ABS plastic, may provide a protective barrierbetween a tip end of the shaft and the topmost end of the insert. Inother embodiments, the insert cap may not be necessary, as the topmostend of the insert is covered by an epoxy layer when the tip end of theshaft is affixed in the hosel bore. By thus forming the main body of thegolf club head around the insert, space that would otherwise be filledby denser metallic material is instead occupied by, e.g., a ceramicmaterial. Mass is thus selectively removed from the hosel and heelportions, thereby accomplishing the goal of moving the center of gravitycloser to the face center.

Other exemplary club heads are seen as being within the spirit and scopeof the present invention. For example, as shown in FIG. 13 and like themethod of FIG. 7, an insert 390 may first by formed at a first step 310by, e.g., injection molding, and the main body of the golf club head maythen be formed around the insert at a second step 320 by, e.g.,investment casting. But at a third step 330, instead of removing onlythe upper part of the insert so as to form the hosel bore of the hoselportion, more of the insert may be removed so as to form an internalcavity below the hosel bore. More specifically, and as shown in FIG. 14,part 392, e.g., at least 50% by volume, or all of the insert may beremoved by, e.g., mechanical agitation, chemical etching, orelectrolytic etching, to form the internal cavity. In some aspects, theinsert may be comprised of a material having high solubility in water oraqueous solutions. In such aspects, the insert may be easily dissolvedout of the golf club head to form the cavity. This cavity may then befilled at the fourth step 340 in FIG. 13 by injecting therein materialsuch as a polymer foam that later solidifies. This fourth step may thusintroduce a vibration dampening material within the club head or allowtuning of the location of the center of gravity by, e.g., varying thedensity of the polymer material. And as in the method of FIG. 7, aninsert cap may then be introduced at a fifth step 350 into the hoselbore so as to rest on the metal shelf delimiting the bottom of the hoselbore.

Yet other exemplary club heads are considered as being within the spiritand scope of the present invention. For example, although FIGS. 10-12and 14 show the insert as extending only to the heel-most extent of thescore lines, this need not be the case. Indeed, as shown in theexemplary golf club head 400 of FIGS. 15-19, the insert 490 may extendfarther into the sole portion or to the toe portion of the golf clubhead. This insert may in fact extend the entire distance from the heelto the toe. Such a configuration may be more feasible in“game-improvement” type golf club heads, which generally have a largersole volume to accommodate such an insert. The golfer using a“game-improvement” club head may also find less objectionable anychanges in sound and/or feel that result from the insert extending intothe striking face. In fact, the presence of the insert may provide avibrational dampening effect and improve feel on off-center impacts. Andas shown in FIG. 19, which shows a cross-section taken along the lineXIX-XIX of the golf club head of FIG. 17, a high density portion 492 maybe co-molded with or otherwise located within the insert at the toeportion. This high density portion may be a metallic material, e.g., atungsten alloy, and it may have a density greater than 10 g/cm³.Including such a high density portion in the insert may be beneficialbecause it can add mass to the toe portion of the golf club head toincrease MOI, it can improve feel of the golf club head upon striking agolf ball, and it may ultimately reduce manufacturing costs.

In the foregoing discussion, the present invention has been describedwith reference to specific exemplary aspects thereof. However, it willbe evident that various modifications and changes may be made to theseexemplary aspects without departing from the broader spirit and scope ofthe invention. Accordingly, the foregoing discussion and theaccompanying drawings are to be regarded as merely illustrative of thepresent invention rather than as limiting its scope in any manner.

What is claimed is:
 1. A golf club head that, when oriented in areference position, comprises: a striking face having a face center anddefining a face plane; a vertical center plane that is perpendicular tothe face plane and extends through the face center; a sole portion; atop portion; a heel portion; a toe portion opposite the heel portion; ahosel portion extending from the heel portion and comprising a hoselbore with an open end for receiving a shaft and a bottom surface, thehosel bore defining a central hosel axis; a rear surface opposite thestriking face that, along a heel-to-toe direction, is substantially flatfrom a heel-most extent of the golf club head to a toe-most extent ofthe golf club head; a center of gravity spaced less than 5 mm from thevertical center plane; a moment of inertia about a vertical axisextending through the center of gravity, Izz, greater than 3,000 g*cm²;and a moment of inertia about a horizontal axis extending through thecenter of gravity, Ixx, greater than 1,000 g*cm², wherein the golf clubhead comprises a first component comprised of a first material having afirst melting point and a first density and a second component having asecond melting point higher than the first melting point and a seconddensity less than the first density, the second component (i) being atleast partially encapsulated by the first component, (ii) extending intothe hosel portion below the hosel bore, and (iii) having a mass lessthan about 5 g.
 2. The golf club head of claim 1, wherein the firstcomponent encapsulates substantially the entirety of the secondcomponent and defines a minimum surrounding wall thickness that is noless than 0.5 mm.
 3. The golf club head of claim 2, wherein the minimumsurrounding wall thickness is no less than 0.75 mm.
 4. The golf clubhead of claim 1, wherein the golf club head further comprises an overallmass and the mass of the second component is less than 1.5% of theoverall mass of the golf club head.
 5. The golf club head of claim 1,wherein the second component comprises a porosity of no more than 40%.6. The golf club head of claim 1, further comprising a cap incommunication with the bottom surface of the hosel bore.
 7. The golfclub head of claim 1, wherein the second component further comprises asubstantially cylindrical portion defining a second central axis coaxialwith the central hosel axis.
 8. The golf club head of claim 7, whereinthe striking face includes a plurality of horizontally extending scorelines and the second component extends to about a heel-most extent ofthe score lines in the heel-to-toe direction.
 9. A method of forming agolf club head comprising the steps of: (a) forming an auxiliarycomponent with an auxiliary material; (b) encapsulating, by aninvestment casting process, the auxiliary component within a golf clubhead body comprising a primary material; and (c) removing a portion ofthe auxiliary component to create a hosel bore with an open end and abottom surface such that an uppermost extent of the auxiliary componentis below the bottom surface, wherein the primary material has a firstmelting point and a first density and the auxiliary material has asecond melting point greater than the first melting point and a seconddensity less than the first density, wherein the golf club headincludes: a striking face having a face center and defining a faceplane; a vertical center plane substantially perpendicular to the faceplane and passing through the face center; a rear surface opposite thestriking face that, along a heel-to-toe direction, is substantially flatfrom a heel-most extent of the golf club head to a toe-most extent ofthe golf club-head; a center of gravity located less than 5 mm from thevertical center plane; a moment of inertia about a vertical axisextending through the center of gravity, Izz, greater than 3,000 g*cm²;and a moment of inertia about a horizontal axis extending through thecenter of gravity, Ixx, greater than 1,000 g*cm².
 10. The method ofclaim 9, wherein forming the auxiliary component comprises an injectionmolding process.
 11. The method of claim 9, wherein a minimumsurrounding wall thickness of the encapsulating auxiliary component isno less than 0.5 mm.
 12. The method of claim 11, wherein the minimumsurrounding wall thickness is no less than 0.75 mm.
 13. The method ofclaim 9, wherein a mass of the auxiliary component is less than 1.5% ofan overall mass of the golf club head.
 14. The method of claim 9,wherein the auxiliary component comprises a porosity no more than 40%.15. The method of claim 9, further comprising inserting a cap incommunication with the bottom surface of the hosel bore.
 16. The methodof claim 9, further comprising the steps of forming an internal cavityby removing at least 50% by volume of the auxiliary component by aprocess selected from the group consisting of mechanical agitation,chemical etching, and electrolytic etching; and injecting a polymericmaterial into the internal cavity.
 17. A golf club head that, whenoriented in a reference position, comprises: a golf club head main bodycomprising: a striking face having a face center and defining a faceplane; a vertical center plane that is perpendicular to the face planeand extends through the face center; a sole portion; a top portion; aheel portion; a toe portion opposite the heel portion; a hosel extendingfrom the heel portion and comprising a hosel bore with an open end and abottom surface, the hosel bore defining a central hosel axis; a rearsurface opposite the striking face that, along a heel-to-toe direction,is substantially flat from a heel-most extent of the golf club head to atoe-most extent of the golf club head; and a first material having afirst melting point and a first density; a center of gravity locatedless than 5 mm from the vertical center plane; a moment of inertia abouta vertical axis extending through the center of gravity, Izz, greaterthan 3,000 g*cm²; a moment of inertia about a horizontal axis extendingthrough the center of gravity, Ixx, greater than 1,000 g*cm²; and anauxiliary component comprising: a heel portion comprising a secondmaterial having a second melting point higher than the first meltingpoint and a second density less than the first density; an upper extentlocated below the bottom surface of the hosel bore; and a toe portionconnected to the heel portion and comprising a third material having adensity greater than the first density.